SQ643X - 1 type pneumatic three-way switch valve for butterfly valves in the form of a switching valve. By three connect body, disc, pneumatic cylinder and connecting rod mechanism. Two butterfly plate are connected by a connecting rod mechanism, and in the open-close position of the opposite. Driven by two pneumatic cylinder in the middle of the butterfly plate complete opening and closing action, another butterfly plate under the action of connecting rod instead of finish. So as to realize the switch of the medium. This valve can be remote automatic control. This valve is suitable for steel, steel rolling dust removal system and other gas, air and high dust content gas medium line control system, can be used a generation of two valves.